Some of these giants had feet 18 ells in length (Deut. R. i.), and the same length is given for the thigh-bone (Buber, “Tanhuma,” Debarim, addition 7). Numerous rows of teeth are also ascribed to them (Hul. 60b). They were very voracious, eating as many as a thousand oxen, horses, and camels each day (Midrash Abkir). Jewish Encyclopedia of 1906
According to Jewish lore, the first inhabitants of Palestine were giants, specifically the Anakim and the Rephaim. Therefore, extra-biblical sources claimed that the other early inhabitants of Palestine were related to these two giant tribes and must therefore have been giants themselves. Consequently, the Avvim of Deuteronomy 2:23 were assigned a relationship to the Rephaim. According to the Genesis Raba 26:7, the Avvim were one of seven groups of “mighty men of old,” the giants of Genesis 6:4, and the Avvim brought the world to ruin.
Chullin 60b connects to giants talking about the Avvim. Here is what the text actually says, speaking of the Avvim: “R. Joseph said: Every one of them had sixteen rows of teeth” (Epstein’s English trans. of the Talmud).